Process of dry creaseproofing cellulosic fabrics with divinyl shlphone



United States Patent 3,106,439 PROCESS OF DRY CREASEPROOFING CELLU- LOSIC FABRICS WITH DIVINYL SULPHON E Leslie Mackenzie Valentine, Manchester, and Brian Frederick Sagar, East Didsbury, Manchester, England, assignors to Tootal Broadhurst Lee Company Limited, Manchester, England, a company of Great Britain No Drawing. Filed Jan. 13, 1960, Ser. No. 2,107 Claims priority, application Great Britain Jan. 17, 1959 7 Claims. (Cl. 8-116) The present invention concerns improvements in the treatment of cellulosicmaterials including woven, knitted and non-woven fabrics for example bonded fibre fabrics.

A process for the chemical modification of cellulosic materials has been suggested which comprises subjecting cellulose or a derivative of cellulose containing cellulosic hydroxyl groups to the action of divinyl sulphone, (CH =CH) SO,, in the presence of a catalyst consisting of a base which is unreactive to divinyl sulphone. It is suggested that the cellulosic material be moistened with an aqueous solution of divinyl sulphone and then treated with an aqueous solution of the alkaline catalyst, and the material washed free of the catalyst at the end of the reaction period, without previously being dried, or alternatively that the catalyst be removed by neutralisa- 'tion. The primary object of this suggested process was to reduce the shrinkage of cotton and regenerated cellulose textile materials and fabrics which are subject to washing, but as a result of the treatment cotton was found to retain creases and mechanical effects, such as pleating, made before treatment and subsequently to retain these creases when washed, and treated fabrics have also been found to resist creasing when in the wet state. Furthermore, treated cotton has been found not to retain chlorine, so that it was not damaged or made yellow by washing in presence of chlorine-containing bleaching agents. Also the effects of the treatment were not removed by severe laundering.

Cotton and regenerated cellulose fabrics treated by this suggested process have little or no ability to resist creasing when dry (dry crease-resistance or dry C.R.) which we prefer to measure by means of the dry recovery machine referred to on page 388 of An Introduction to Textile Finishing? by J. T. Marsh, published by Chapman & Hall in 1948. However, the ability to dry smooth after laundering and the resistance to creasing when wet can be good as shown by the smooth drying index (S.D.I.) which we prefer to measure by use of an apparatus consisting of (l a crease maker, (2) a drying cabinet, and (3) a crease gauge.

According to this test specimen strips of the fabric are cut in both warp and weft directions. These are wetted out, squeezed through a small domestic mangle, and inserted in the crease maker in order to form a sharp double crease. The specimen is next dried for half an hour and during drying the crease inserted in the wet fabric diminishes. The 5.12.1. figure is obtained from the extent of this recovery anii it indicates the ability of the fabric to recover from creases formed during normal domestic washing.

The extent of this recovery is measured by placing the dried sample in the cabinet of the crease gauge and the angle of the residual crease is measured from observation of the shadow cast by the crease when illuminated by a directional light sou e. The smaller the figure obtained by this test the bet a s the fabrics property of needing little or no ironing a er washing.

A lack of dry cr e-resistance can be a severe disadvantage and we have now discovered a process by which an improved balance between dry crease-resistance and 3,106,439 Patented Oct. 8, 1963 smooth drying index can be obtained using an alkali catalysed divinyl sulphone system.

According to the present invention a process for the chemical modification of cellulosic material is provided which comprises treating cellulose or a cellulose derivative containing cellulose hydroxyl groups with divinyl sulphone and an alkaline or potential alkaline catalyst which is unreactive to divinyl sulphone and drying the treated material by heating without previous removal of the catalyst.

Fabrics, especially cotton and rayon fabrics, treated by the process of the present invention have improved dry crease-resistance as compared with the material before treatment. Improvement in the dry crease-resistance of the material is obtained if the material, after being treated with the divinyl sulphone in the presence of a suitable alkaline catalyst is dried by heating under mild conditions that is at a temperature below 100 C. and preferably below C. The dry crease-resistance can be enhanced if the dried sample is then baked. We prefer therefore in order to obtain the best and most uniform results to dry the impregnated and mangled cloth on a stenter at as low a temperature as possible and then bake it at l00l70 C. for l-S minutes. The dry crease-resistance increases as the temperature of baking is increased.

We believe that the good dry crease-resistance is obtained because the cellulose is in a dehydrated and collapsed state when the major portion, if not the whole, of the reaction between the cellulose and the divinyl sul phone takes place although naturally we do not wish to be limited to this theory.

We prefer to treat woven fabrics made from cellulosic fibres. Such fabrics treated according to this invention have the properties referred to above in connection with the previously suggested process, in addition to the property of improved dry crease-resistance. A further advantage of the process according to the present invention is that the reaction is not very sensitive to curing conditions so that good effects can be obtained over a wide range of conditions and the process does not require strict control of temperature or time of baking which is necessary to effect the reaction between the divinyl sulphone and the cellulose.

Cellulosic materials treated according to this invention also have the property of retaining even when washed creases and mechanical effects such as pleated, glazed and embossed effects made before or during treatment. It is also possible by the process of this invention to improve the fixation of starch and starch products.

It is necessary to use an alkaline catalyst in order to bring about the reaction between the divinyl sulphone and the cellulosic material. Any catalyst giving a bath pH greater than, or equal to, 8.5 and which does not react with divinyl sulphone can be used such as, for example, sodium hydroxide, sodium carbonate or sodium metasilicate. If the bath pH is greater than 12.0, however, we find that the bath 'life is too short for convenient operation of a one-bath process, and we find that a two-bath process is necessary. We have found that divinyl sulphone in the presence of aqueous alkali is converted, at a rate proportional to the concentration and basic strength of the alkali, into products that do not react with cellulose. Thus, at a bath pH of 13.5, obtained with 0.5 molar sodium hydroxide, the time for the loss of 25% of the divinyl sulphone is estimated to be about 1 minute. This estimation is based on our experimentally determined figure of 8.2 10- reciprocal minutes for the specific hydroxyl ion catalysed reaction rate constant. However, in addition to specific hydroxyl ion catalysis we have found that the conversion of divinyl sulphone into unreactive products is also catalysed by undissociated bases. This phenomenon, known as general base catalysis, is fully described in many standard physical chemistry text books (cf. R. P. Bell, Acid- Base Catalysis, Oxford University Press, Oxford, 1941). Accordingly, if one wishes to operate a one-bath process, the catalyst must be such as to give a bath pH within the range 85-120 and preferably a catalyst concentration not greater than 0.2 molar. A further advantage of operating within this range of pH is that reaction between the divinyl sulphone and the cellulose in the swollen state is less than it is at higher pH values.

Alternatively it is possible to operate a one-bath process by using a substance which gives a bath pH not greater than 12.0 and which on the concentration and/ or heating of liquor from the bath, breaks down to liberate a more alkaline substance, that is to say by using a potential alkali catalyst.

We prefer to use as a potential alkali catalyst, sodium bicarbonate, which gives a low bath pH but is converted into a stronger alkali, sodium carbonate, when heated. With sodium bicarbonate, therefore, one obtains a long bath life'and yet it breaks down to form an alkali which gives a high degree of fixation on curing. Also, since the alkalinity from sodium bicarbonate is not fully developed until it is heated, the use of this catalyst minimises the reaction of divinyl sulphone with the cellulose whilst the latter is in the wet or swollen state.

The cellulosic material which may be treated according to this invention may include cotton, rayonor linen fabrics or fabrics of cellulose derivatives containing cellulosic hydroxyl groups such as secondary cellulose acetate. In the case of fabrics these can be either woven or non-woven fabrics. Mixtures of cellulosic with nonoellulosic fibres, for example wool or nylon, may be treated but we prefer to treat mixtures containing at least 50% of cellulosic fibres.

The invention will be more clearly understood by reference to the following examples which are purely illustrative:

Example 1 A sample of cotton fabric was impregnated with 100 mls. of a solution containing mls. of divinyl sulphone and 5 mls. of a 2 molar solution of sodium metasilicate. The sample was squeezed by passing it between the bowls of a mangle adjusted so that the sample retained about 80% by weight of liquor and dried at 55 C. for 25 minutes. It was then immediately baked at 120 C. for 2 minutes. After washing in a boiling solution containing 0.25% soap and 0.25% soda ash for 5 minutes it had the following properties:

Percent Fabric weight gain (79% of theoretical maximum) 3.75 S.D.I. across the warp 8.2 Dry C.R. (average of warp and weft) 3.40

Example 2 A sample of cotton poplin shirting was impregnated with a 5% v./v. solution of divinyl sulphone that was tenth normal with respect to sodium hydroxide. After mangling and drying the sample was baked for 2 minutes at 160 C. It was given a similar wash-off to the sample in Example 1 and had the following properties:

Percent Fabric weight gain (86% of theoretical maximum) 4.11 S.D.I. across the warp 6.9 Dry C.R. (average of warp and weft) 3.40

Example 3 Two similar samples of cotton fabric were impregnated with a solution, 1000 mls. of which contained 0.4 gm. mole of divinyl sulphone and 0.1 gm. mole of sodium carbonate. The samples were mangled so that they retained about of the liquor and then placed in a convector drying cabinet with an air temperature of 55 C. for 25 minutes. The samples were then dry to the touch. One of the samples was then baked for 2 minutes at 130 C. after which they were washed off together in a boiling solution containing 0.25% soap and 0.25% soda ash for 5 minutes. They then had the following properties:

Dried and Dried then baked only, at: 120 C. percent for 2 minutes, percent Sample weight gain 1. 70 2. 33 S.D.I. across the warp 12. 0 10.5 Dry OR. (average of warp and weft) 2. 6O 3. 08

Example 4 A pair of samples of the same material as in Example 3 was treated in an exactly analogous manner using an impregnating solution that was 0.4 molar with respect to divinyl sulphone and 0.5 molar in sodium hydroxide. This bath had to be used within a minute or two of adding the alkali; precipitation occurred after 9 minutes. The samples had the following properties:

Dried Dried and onl then baked, percent percent Sample weight gain 3. 59 3. 5-1 S.D.I. across the warp 12.0 10. 5 Dry QR. (average of warp and weft) 2. 58 3. 02

Example 5 A sample of rayon material was impregnated with an aqueous solution mls. of which contained 5.5 mls. of divinyl sulphone and 0.4 g. of sodium hydroxide. The sample was mangled to about liquor retention and dried before being baked at 110 for 2 minutes. After being washed in a boiling solution containing 0.25% soap and 0.25% soda ash for 5 minutes, the sample had the following properties:

Percent Fabric weight gain (84% of theoretical maximum).. 5.7 S.D.I. (across the warp) 15.5 Dry C.R. (average of warp and weft) 2.75

Example 6 Dried Dried and baked only, ()4 min. percent at C-.),

percent Sample weight gain S.D.I. across the warp 32. 2 12: 2 Dry C.R. (average of warp and weft) 2. (10 2. 00

Example 7 Here the treatment was as in Example 6 but the bicarbonate was increased to 0.25 molar and one of the samples was baked for 8 minutes at 100 C. The following results were produced:

Both solutions from Examples 6 and 7 showed no signs of precipitation even after four weeks.

We claim:

1. Process for the chemical modification of fabric containing at least 50 percent of fibres selected from the group consisting of fibres of cellulose and fibres of cellulose derivatives having free hydroxyl groups, comprising applying to the fabric aqueous solutions of divinyl sulphone and a member which is unreactive to divinyl sulphone and which is selected from the group consisting of alkaline catalysts and catalysts which are alkaline when heated so as to effect the application of said solution at a pH of at least 8.5, and drying the fabric by heating at a temperature below approximately 100 C. without pre vious removal of the selected catalyst until improved dry crease-resistance of said fabric is obtained.

2. Process as in claim 1 wherein the material is dried at a temperature below approximately C.

3. Process as in claim 1 wherein the dried material is baked at a temperature between approximately C. and C. for a period between approximately 1 and 5 minutes.

4. Process as in claim 1 wherein the aqueous solutions are applied to the fabric at a maximum pH of 12.0.

5. Process as in claim 1 wherein the selected catalyst concentration is a maximum of 0.2 molar.

6. Process as in claim 1 wherein said alkaline catalysts are selected from the group consisting of sodium hydroxide, sodium carbonate and sodium metasilicate.

7. Process as in claim 1 wherein the selected catalyst is sodium bicarbonate which is converted into more alkali sodium carbonate upon heating thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,343,920 Maxwell Mar. 14, 1944 2,482,756 Ford Sept. 27, 1949 2,524,399 Schoene Oct. 3, 1950 2,774,691 Schroeder Dec. 18, 1956 2,785,949 Kress Mar. 19, 1957 OTHER REFERENCES Reid: Textile Research Journal, March 1958, pp. 242 251. 

1. PROCESS FOR THE CHEMICAL MODIFICATION OF FABRIC CONTAINING AT LEAST 50 PERCENT OF FIBERS SELECTED FROM THE GROUP CONSISTING OF FIBRES OF CELLULOSE AND FIBRES OF CELLULOSE DERIVATIVES HAVING FREE HYDROXYL GROUPS, COMPRISING APPLYING TO THE FABRIC AQUEOUS SOLUTIONS OF DIVINYL SULPHONE AND A MEMBER WHICH IS UNREACTIVE TO DIVINYL SULPHONE AND WHICH IS SELECTED FROM THE GROUP CONSISTING OF ALKALINE CATALYSTS AND CATALYSTS WHICH ARE ALKALINE WHEN HEATED SO AS TO EFFECT THE APPLICATION OF SAID SOLUTION AT A PH OF AT LEAST 8.5, AND DRYING THE FABRIC BY HEATING AT A TEMPERATURE BELOW APPROXIMATELY 100*C. WITHOUT PREVIOUS REMOVAL OF THE SELECTED CATLYST UNTIL IMPROVED DRY CREASE-RESISTANCE OF SAID FABRIC IS OBTAINED. 